This is adapted from the book, Eat Smart, Play Hard, by RW USA Nutrition Editor Liz Applegate.
Branched-chain amino acids, or BCAAs, have been a hot topic for years, and they do show promise for endurance athletes. Several well-designed studies suggest that supplemental BCAAs may improve your exercise performance and help prevent the muscle damage that can occur with heavy training.
BCAAs, along with 17 other amino acids, are the building blocks that form all of the protein in your body. They come mostly from meats and beans; and during 2 or more hours of exercise, your body breaks down these amino acids and burns them for energy. If this happens often enough, your muscle protein supply starts to dwindle. Taking a BCAA supplement might help.
Researchers from the University of Tasmania in Australia investigated the effects of BCAA supplementation on muscle damage in a group of cyclists. The cyclists took either a placebo or 12 grams (double the amount from dietary sources) of BCAAs daily for 6 days. Immediately following the supplementation period, they cycled hard for 2 hours. After this exercise session, researchers took blood samples every hour for several hours, then once a day for 4 days. The researchers then measured muscle-tissue damage based on various enzyme levels in the blood. Compared to the placebo group, cyclists who took BCAA supplements showed less muscle damage, leading researchers to believe that the supplement may have helped replace the BCAAs lost during exercise.
Before you try BCAA supplementation, remember that by far the best way to maintain adequate muscle tissue is by getting enough calories and protein. And while those in the study had no adverse side effects from BCAA supplementation, 6 days is hardly enough time to determine long-term side effects.
My recommendation: Although branched-chain amino acids show promise, especially for endurance athletes, wait for more research to determine the safety of this supplement before you start popping one every day. Instead, make sure you are eating 75 to 100 grams of protein a day.